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TOPIC: Sneak preview
http://groups.google.com/group/entstrees/browse_thread/thread/826c8f9efe163151?hl=en
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== 1 of 2 ==
Date: Wed, Sep 24 2008 7:25 am
From: dbhguru@comcast.net
ENTS,
Folks, it is time to reconsider our two ENTS methods of ranking the
size of trees: ENTSPTS and TDI. The TDI system is sound. No
modifications needed there, but ENTSPTS is ailing, the reason being
that the number of points awarded does not track well enough with
increases in trunk volume . The following table compares the effect
of tree size increases using the old way of calculating ENTSPTS (
height x circumference) , a proposed new way of calculating ENTSPTS
( [height x Circumference ^2]/100), and an abbreviated version of
the champion tree formula ( 12 x circumference + height).
Height 
Circ 
VOLCONE 
ratio 
ENTSPTS 
ratio 
ENTSPTS2 
ratio 
Champ Tree Pts 
ratio 
50 
8 
84.8 

400 

32 

146 

50 
12 
190.8 
2.3 
600 
1.5 
72 
2.3 
194 
1.3 
50 
16 
339.2 
4.0 
800 
2.0 
128 
4.0 
242 
1.7 
100 
8 
169.6 
2.0 
800 
2.0 
64 
2.0 
196 
1.3 
100 
12 
381.6 
4.5 
1200 
3.0 
144 
4.5 
244 
1.7 
100 
16 
678.4 
8.0 
1600 
4.0 
256 
8.0 
292 
2.0 
150 
8 
254.4 
3.0 
1200 
3.0 
96 
3.0 
246 
1.7 
150 
12 
572.4 
6.8 
1800 
4.5 
216 
6.8 
294 
2.0 
150 
16 
1017.6 
12.0 
2400 
6.0 
384 
12.0 
342 
2.3 
Looking at the table, we see that the ratio of the volume of the
largest tree to the volume of the smallest is 12 to 1. The ratio of
ENTSPTS of the largest tree to the smallest is 6 to 1. The ratio of
modified ENTSPTS of the largest to the smallest tree is 12 to 1
(just what we want), and the ratio of modified champion tree points
of the largest to smallest tree is 2.3 to 1. The change in modified
ENTSPTS tracks perfectly with conical volume. Each ratio in the
above table is the current entry divided by the first entry in the
respective column, not the preceding entry in the column. The
purpose of the ratio columns is to show how points track with
changes in volume as measured by a form such as the cone or
paraboloid.
The reason I chose a scaling factor of 100 for modified ENTSPTS is
to bring the point total more in line with numbers that come from
the champion tree formula. Additionally, it is computationally
simple. I leave out hypothetical crown spread in the table. However,
were we to include realistic crownspreads for the size trees
indicated by height and circumference, the ratio of the points of
the largest tree to the smallest would increase slightly  perhaps
2.5 to 1.
I've discussed the new system of ENTSPTS with Ed off list. Ed is
solidly behind it. Ed also mentioned that John Eichholz had once
before pointed out the value of C^2 versus C as the factor dealing
with circumference. I mentioned the proposed new method briefly to
Will in a recent phone conversation and told him I'd shortly present
some analysis. The above table is the first step in that direction.
Thoughts anyone?
Bob
== 2 of 2 ==
Date: Thurs, Sep 25 2008 2:02 am
From: Beth Koebel
Bob,
Not being a math major (I had to drop CAL I because I couldn't
understand it), it looks like you are using a cone to measure
the volume as the "gold standard" and then using
the new ENTPTS2 to get the measurements that are often taken,
height and circumfence, to match it. If this is the case, then
would this work also for trees like palms or any other tree in which
there is a trunk without branches for say 50 or so feet then a
relatively flat crown(umbrella shaped)? How about the classic
hardwood shaped tree (golf ball on a tee)?
BTW, I am not going to be able to make it to the ENTS gathering in
Oct. as it is too close to my projected closing. Sorry, I
wish I could've made it. Maybe the next one.
Beth
== 2 of 11 ==
Date: Thurs, Sep 25 2008 6:06 am
From: dbhguru@comcast.net
Beth,
The proposed ENTS point formula admittedly works best for trees with
long straight trunks that can be modeled with a regular geometrical
form, principally a neiloid, cone, or paraboloid. I chose the cone
for illustration purposes, but either of the other two forms would
have worked just as well.
The question of what kind of formula works for a big spreader like
the live oaks that Larry measures is probably not going to be
adequately determined for a long time. There is just too much wood
tied up in the complex network of limbs. The ENTSPTS formula is not
the answer for trees of that shape, but then neither is the champion
tree formula. Consider the table below.
HGT 
CIR 
SPD 
CHP PTS 
ENTSPTS 
50 
12 
120 
224 
72 
65 
24 
120 
383 
374.4 
130 
24 
120 
448 
748.8 
For trees with spreads of 120 feet, we know there is lots of wood
committed to the limbs. Looking at the entries in the table, it is
apparent that ENTSPTS does not capture limb wood. The champion tree
formula actually does better, but going from rows 2 to 3 is just not
logical for the champion tree formula. A 130foot tall tree with a
120foot crownspread implies a lot more wood than the spread of
points of 383 to 448 indicates.
The problem we're experiencing in calculating an absolute number of
points for a tree stems from the one size fits all approach. I
understand that it was for simplicity's sake and to try to get the
general public involved, but the formula doesn't work well enough
for a group like ENTS.
For a system of relative comparisons, TDI works well and we may
never get beyond that, i.e. relative comparisons. However, for white
pines in New England, I need more of an absolute measure. The amount
of limb mass for a tall, straight conifer may not be more than 5% or
6% of trunk volume. So, I don't have to worry too much about the
limbs and can apply the proposed formula. By contrast, the limb
volume versus trunk volume ratio may approach 50% for live oaks. I
wouldn't apply to formula to trees of those shapes. So, the search
must go on.
I apologize to the list for not making it clear that I had conifers
in mind for the proposed formula. Very clumsy of me.
Sorry you won't be able to make it to the rendezvous. The one in
2009 will be in Cook Forest. That is considerably closer to help for
time and expense travel.
Bob
== 3 of 11 ==
Date: Thurs, Sep 25 2008 9:01 am
From: "Edward Forrest Frank"
Bob,
I think you are equivocating too much. Your proposed formula
provides a number that is proportional to the trunk volume of a tree
with any regular geometric shape or combination of shapes ranging
from neloid, to conical, to parabaloid. It is approximately
equivalent to the 1/8 the volume of a cylinder of the same
circumference and height. Individual trees even within a species
vary quite a bit, so the formula will not replace the volume
measurements of an individual tree, but will trend parallel to the
volume of trees in general. If a particular tree species tended to
fall in a given range, say 30 to 40% of the volume of a cylinder of
the same size, then a simple constant  a number could be
multiplied by the ENTS formula to determine what the typical trunk
volume or the range of typical trunk volumes would be for a tree of
that species for those basic height and girth measurements. I might
expect that different tree species may have a tendency toward one
typical shape or another, or that trees of a certain age range may
may have a tendency toward one shape over another. But in all cases
the proposed ENTS points will in general trend in the same direction
as trunk volume. As Bob says the formula only deals with the trend
of trunk volume and not with the volume of the tree limbs. Trees
with broadly flaring bases or tops that are broken off will be
outliers to the overall trends also. Since volume is proportional to
the square of the circumference for any regular geometric shape, it
is certainly a much better rough approximation of tree volume trends
than the simple product of height and girth..
Ed
== 4 of 11 ==
Date: Thurs, Sep 25 2008 10:14 am
From: dbhguru@comcast.net
Ed,
I'm content with the formula as a replacement for Cir x Hgt. For
trees with long trunks, I think it is definitely preferable to the
champion tree formula. We're making progress.
Bob
